In-House Metalwork: Brass, PVD and Powder Coating Lines

2026-09-10 · Factory & Craft · Rosy Rose Trade Journal

In-House Metalwork: Brass, PVD and Powder Coating Lines

Metal is the part of a furniture programme that fails most visibly. Wood can be refinished, upholstery can be re-covered, but a leg that discolours, a frame that blisters at a weld, or two chairs whose brass trims do not match after a second container has arrived cannot be repaired on site. For importers and specifiers, metal finishing is worth understanding because it is where a factory's real capability shows — and where a factory that subcontracts its finishing quietly loses control of colour, lead time and quality.

Why metal finishes become the weakest link

Metal is exposed. It is touched more often than any other surface on a chair, it sits at the lowest point of a piece where trolleys and cleaning equipment make contact, and it is assembled from several parts that must end up looking identical. A finish that is specified by name — "antique brass", "champagne gold" — leaves the entire technical decision with the supplier. Two suppliers will read the same words and deliver different tones, different sheens and completely different durability.

The useful distinction is between what the colour is and how it is achieved. The same visual gold can sit on solid brass, on a plated layer, on a PVD coating or on a powder-coated aluminium frame, and those routes differ in abrasion resistance, colour stability, cost and repairability by a factor of several times.

The cost of getting it wrong is not the cost of the finish; it is the cost of the claim. A finish failure on a delivered container cannot be repaired by a local upholsterer or a joiner on site. The parts come back, or they are replaced, and the freight alone often exceeds the value of the metal components in question. That asymmetry is why finish decisions deserve the same attention as a foam density or a fabric abrasion figure, and why we keep plating, PVD and coating inside our own production rather than buying finished metal from a trade supplier.

Solid brass, plated brass and antique brass

Solid brass is the benchmark for premium metalwork. It can be polished to a high lustre, hand-relieved, brushed or given a lacquer; it patinates naturally where the lacquer is deliberately omitted; and it can be re-polished decades later. It is also one of the most expensive routes and the heaviest, which matters when a piece is container-loaded by volume rather than by weight. Solid brass is normally reserved for trims, handles, inlay strips and feature frames rather than complete structures.

Plated brass takes a steel or zinc-alloy base and deposits a brass layer on top. It is the standard route for quantity programmes, and its quality depends almost entirely on layer thickness and preparation. Thin decorative plating over a poorly cleaned substrate is where flaking at weld zones and on cut edges comes from. Antique or distressed finishes are usually a two-stage process: plate first, then oxidise and relieve by hand, which is why they cannot be made perfectly identical piece to piece and why a tolerance for variation should be written into the order.

PVD: a hard, thin, colour-stable layer

Physical vapour deposition deposits a metal layer in a vacuum chamber, producing a very thin coating that is significantly harder than electroplating. In practice, PVD is chosen for contact pieces: chair frames, table bases, cabinet handles and any surface expected to keep its appearance through years of handling.

Two properties matter to a buyer. First, colour stability: PVD golds and champagnes do not fade the way a lacquer over plated brass can, and they resist the fingerprint and oxidation problems that plague bright plating in humid climates. Second, film thickness is measured in microns, so the process is unforgiving of substrate defects — the base metal must be polished before coating, because PVD will telegraph every scratch. Where a programme needs a specific tone, the sample bar is the contract: an approved physical sample, sealed and signed, is the only reference that settles a dispute later.

Production reality adds one more constraint. A PVD chamber has a maximum size, so large one-piece frames may have to be split into coated sub-assemblies and joined afterwards, or routed to a different process. Batch colour also drifts slightly between coating runs, which means a large order should be coated in as few batches as the chamber allows and the parts kept together through assembly. For a buyer, the practical question is a simple one: how many batches will my order be split into, and how will you keep them matched?

Powder coating and architectural-grade coatings

Powder coating is an electrostatically applied, oven-cured polymer finish, and it remains the most cost-effective durable finish for aluminium and steel frames, garden-adjacent contract pieces and structural elements. The variables are pretreatment (degrease, phosphate or chromate, rinse), powder chemistry (polyester, epoxy-polyester, or a formulation rated for exterior exposure) and film thickness, typically 60 to 100 microns.

Powder is where a factory can cut corners invisibly: skip the pretreatment stage and the coating will pass every visual inspection on the day and then chip along every edge within a year. That is precisely why finishing belongs in-house. When the plating, coating and PVD lines sit under the same roof as the metal shop, the sequence from weld, through grinding and polishing, to coating is scheduled as one flow.

Curing is the other invisible variable. A powder coating that is under-cured will look correct on the day and fail within months, because the polymer network never finished forming. Cure is controlled by time at temperature rather than by temperature alone, and thin or complex parts absorb heat differently from heavy flat ones. The same logic governs the oven cycle after a wet-paint stage, which is one reason a controlled paint line with recorded oven settings outperforms open-booth spraying even when the operator is equally skilled.

Comparing the three routes

Surface preparation is the real specification

Almost every metal failure traces back to preparation rather than to the coating. Weld spatter, grinding marks, oil residue and oxide all sit between the substrate and the finish. In our metal shop, every frame moves through weld dressing, grinding and a polishing stage before it is allowed near a coating line, and pretreatment tanks are checked on a schedule rather than by eye. It is unglamorous work, and it is the difference between a finish that survives a hotel refurbishment cycle and one that does not.

Buyers can protect themselves with three specification items: state the finish route rather than only the colour, require a film thickness or layer thickness figure, and require an approved physical sample retained by both parties.

Matching finishes across a set

Colour matching is a batch problem. Legs, trims, handles, hinges and glass frames may be produced on different lines on different days, and each line has its own drift. On a mixed-material programme the risk multiplies: a champagne trim on a wood cabinet must read as the same champagne as the trim on an upholstered chair three months later.

The countermeasures are simple and boring: fix one reference sample per finish per programme, keep it with the project file, run all metal for a single order in one batch where volume allows, and photograph finished parts under fixed lighting for the shipment record. We keep a physical reference bar for each active finish so a reorder placed a year later can be checked against the original rather than against a memory of it.

Specifying metal finishes in an enquiry

A metal specification should state the base metal, the finish route, the tone and sheen reference, the required thickness, the environment the piece will live in, and whether the finish must be repairable on site. Where a piece is part of a full in-house production flow, the factory should be able to tell you which department performs each step — and whether any step leaves the building.

If a supplier cannot say who does the plating or the coating, that is the answer.

Inspecting metal before it ships

Metal should be inspected as a separate discipline at pre-shipment stage, not as a footnote on the furniture checklist. The items worth recording are colour against the retained sample, coating coverage on hidden faces and inside tubes, adhesion at edges and weld zones, surface defects, and consistency across the parts of a single set. A cross-hatch adhesion test on a sample taken from the same batch is a cheap way to find a pretreatment problem before a container leaves. The same logic extends to the coating technology choices covered in our note on PVD, powder coat and plating for contract furniture, which goes deeper into the process controls behind each route.

To discuss a finish programme, send a reference image, the base metal and the expected volume to our metal and finishing team, or reach the factory on WhatsApp at +86 188 2788 2512 — we will send back a sample bar, a finish route and a realistic lead time for a trial batch.